Development and validation of a simple HPLC-MS/MS method for the quantification of methylmalonic acid in human serum without a derivatization step.

A simple and rapid HPLC-MS/MS analytical method was developed and validated for the determination of methylmalonic acid (MMA) in human serum without a derivatization step. Serum samples (200 μl) were pretreated using a simple method based on ultrafiltration using a VIVASPIN 500 ultrafiltration column. Chromatographic separation was achieved on a Luna Omega C18 column with a PS C18 precolumn guard by gradient elution using 0.

Diastereoselective synthesis of (±)-trichodiene and (±)-trichodiene-D as analytical standards for the on-site quantification of trichothecenes.

The ubiquitous genus is responsible for the spoilage of vast amounts of cereals and fruits. Besides the economic damage, the danger to human and animal health by the concomitant exposure to mycotoxins represents a serious problem. A large number of species produce a variety of different mycotoxins of which the class of trichothecenes are of particular importance due to their toxicity.

SARS-CoV-2 rapid antigen testing in the healthcare sector: A clinical prediction model for identifying false negative results.

Objectives: SARS-CoV-2 rapid antigen tests (RAT) provide fast identification of infectious patients when RT-PCR results are not immediately available. We aimed to develop a prediction model for identification of false negative (FN) RAT results.

Methods: In this multicenter trial, patients with documented paired results of RAT and RT-PCR between October 1 2020 and January 31 2021 were retrospectively analyzed regarding clinical findings.

Pro-angiogenic Activity Discriminates Human Adipose-Derived Stromal Cells From Retinal Pericytes: Considerations for Cell-Based Therapy of Diabetic Retinopathy.

Diabetic retinopathy (DR) is a frequent diabetes-associated complication. Pericyte dropout can cause increased vascular permeability and contribute to vascular occlusion. Adipose-derived stromal cells (ASC) have been suggested to replace pericytes and restore microvascular support as potential therapy of DR.

Monitoring matrix remodeling in the cellular microenvironment using microrheology for complex cellular systems.

Multiple particle tracking (MPT) microrheology was employed for monitoring the development of extracellular matrix (ECM) mechanical properties in the direct microenvironment of living cells. A customized setup enabled us to overcome current limitations: (i) Continuous measurements were enabled using a cell culture chamber, with this, matrix remodeling by fibroblasts in the heterogeneous environment of macroporous scaffolds was monitored continuously. (ii) Employing tracer laden porous scaffolds for seeding human mesenchymal stem cells (hMSCs), we followed conventional differentiation protocols.

First Synthesis of -Altenuene-D Suitable as Internal Standard for Isotope Dilution Mass Spectrometry.

Metabolites from fungi exhibit a variety of biological properties such as phytotoxic, cytotoxic, or antimicrobial activity. Optimization of a literature procedure culminated in an efficient total synthesis of -altenuene as well as a stable isotope-labeled derivative suitable for implementation in a LC-MS/MS method for mycotoxin analysis.

Mesenchymal stromal/stem cells as potential therapy in diabetic retinopathy.

Diabetic retinopathy (DR) is a multifactorial microvascular disease induced by hyperglycemia and subsequent metabolic abnormalities. The resulting cell stress causes a sequela of events that ultimately can lead to severe vision impairment and blindness. The early stages are characterized by activation of glia and loss of pericytes, endothelial cells (EC) and neuronal cells.

Total Synthesis of Putative 11-epi-Lyngbouilloside Aglycon.

We report here the total synthesis of 11-epi-lyngbouilloside aglycon. Our strategy features a Boeckman-type esterification followed by a RCM to form the 14-membered ring macrolactone and a late-stage side chain introduction via a Wittig olefination. Overall, the final product was obtained in 20 steps and 2% overall yield starting from commercially available 3-methyl-but-3-enol.

Improved synthesis of (+/-)-trichodiene--a volatile marker for trichothecene mycotoxins.

Trichodiene is the first and only volatile intermediate in the biosynthesis of Fusarium mycotoxins and its detection in the gas-phase might therefore be of potential interest as a marker for food safety analysis. We herein present an improved diastereoselective synthesis of trichodiene which can be used as an analytical standard for a headspace gas chromatography / mass spectrometry method to be developed.

Lyngbouilloside and related macrolides from marine cyanobacteria.

Lyngbouilloside and the related macrolides lyngbyaloside, lyngbyaloside B and lyngbyaloside C have attracted a lot of attention over the past decade due to their intriguing architecture, their natural scarcity and their potential biological activities. This review aims to showcase the various strategies that have been used to access these natural products.

Catalysis-based enantioselective total synthesis of myxothiazole Z, (14S)-melithiazole G and (14S)-cystothiazole F.

A common strategy for the stereoselective and protecting group-free total synthesis of the myxobacterial antibiotics myxothiazole Z, (14S)-melithiazole G and (14S)-cystothiazole F is described featuring an asymmetric organocatalytic transfer hydrogenation, a palladium-catalyzed Stille coupling and a cross-metathesis as the key steps.

Total synthesis of nominal lyngbouilloside aglycon.

The first enantioselective total synthesis of the originally assigned structure of lyngbouilloside aglycon has been achieved using a particularly flexible route featuring an acylketene macrolactonization of a tertiary methyl carbinol as the key step. Comparison of the C13 chemical shifts of our synthetic aglycon with the ones pertaining to natural lyngbouilloside and lyngbyaloside C resulted in a possible stereochemical reassignment of the C11 stereogenic center.

A concise total synthesis of melithiazole C.

A short and convergent synthesis of the myxobacterial antibiotic melithiazole C is described featuring a highly E-selective cross-metathesis as the key step.

Synthesis of gamma,delta-unsaturated-beta-keto lactones via sequential cross metathesis-lactonization: a facile entry to macrolide antibiotic (-)-A26771B.

A simple access to gamma,delta-unsaturated-beta-keto lactones is presented, allowing a rapid total synthesis of the naturally occurring 16-membered macrolide antibiotic (-)-A26771B via cross metathesis, asymmetric dihydroxylation, and lactonization as the key steps.